O-15 PET activation studies of 15 severely dyslexic men and 25 controls indicate: (1) reduced left parietal flow in the resting state, (2) a failure of activation in left posterior temporoparietal regions during phonological processing, (3) normal activation of mid to anterior language cortex during a syntax task and normal language lateralization, and (4) reduced right temporal activation near the region of the planum during our tonal memory task. These results suggest more focal left-sided cortical dysfunction for language processing than previously hypothesized, as well as right-sided dysfunction. MRI data analysis for 23 dyslexic men and 21 controls, is testing a hypotheses of unusual temporal lobe asymmetry, due to an increase in the size of the right planum, and widening of the posterior corpus callosum. Any increase in the size of right planum will be related to PET findings on the "right hemisphere" task. Preliminary O-15 PET results on three autistic patients with unusual calendar-calculating skills and six controls indicate low whole brain blood flow, elevated normalized parietal ratios across states (rest and several tasks) and increased temporoparietal activation/decreased left frontal activation during calender calculating in savants relative to controls.